1 . Field of Invention
The invention offers a method to control and eliminate the infestation of zebra mussels and other encrustaceous organisms attaching to underwater surfaces, structures, and critical devices. The infestation of these encrustaceous organisms has significant impact on the efficient operation of municipal and industrial facilities, and marine shipping. This zebra mussel problem will expand as it continues to proliferate in estuaries and rivers contiguous to the Great Lakes and other fresh water locations. Marine encrustations historically have been problematic for water users.
2. Description of the Prior Art
This bivalve mollusk Dreissena polymorpha commonly known as the zebra mussel colonized Lake St. Clair (Ontario, Canada) in 1986 as a result of ballast water discharge from sea going ships. It is now widely accepted that the zebra mussel has spread to all of the Great Lakes and will eventually inhabit most of the continent's freshwater areas unless a control can be found. The mussels present a problem because they clog water intake areas and equipment, diminishing water flow. It has been estimated that the mollusk could cost the Great Lakes Basin $500 million a year. This problem will continue to expand as the mussel continues to extend its range in estuaries and rivers contiguous with the Great Lakes and elsewhere. The zebra mussel infestation in both estuarine and riverine systems appears to be following the same explosive growth pattern as was evidenced in Lake Erie and other Great Lakes. Moreover, the entire Mississippi River drainage system is thoroughly infested or has an inoculum population of zebra mussels that will impact facilities across the Midwestern and eastern U.S.
The success of invaders and the problems they cause for utility facilities will depend largely on physical parameters like the hydraulic characteristics and availability of colonization sites of in-house underwater structural features. Some potential sites where zebra mussels have become problematic are strainers of all sizes and types including trash racks, metering and monitoring devices, direct connect cylinder recesses, valve recesses, vat and cistern walls, and many other sites. An important application of air injection is to reduce breeding populations of zebra mussels adjacent to water intakes, thereby substantially reducing the influx of veligers to the facility. Design characteristics of a specific device or treatment area will dictate the application and deployment strategy of the air diffuser. The diversity of interference points would ideally be suited by a utilitarian method of zebra mussel control. Air diffusers and injectors will not meet all of the mussel control needs, however, they will be effective for many applications. For clarification, air diffusers deliver a broad band of bubbles whereas air injectors deliver a focused stream of air bubbles. Air "injection" refers to both.
The air injection technique is focused at specific problematic sites in the industrial settling to prevent zebra mussel (Dreissena polymorpha Pallas) veligers from settling, and to evacuate adults that have previously colonized. The air injection method has the capacity of eliminating zebra veligers prevented from settling on critical underwater components such as metering and monitoring devices. Air injection is believed to be the first environmentally non-invasive technique to have definitively demonstrated zebra mussel control on a large scale. The principle of the technique and actual apparatus design are remarkably flexible, and thus will integrate well with a variety of different industrial site specific configuration requirements.